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Sometime early last year, an arbitrary >15 minute limit was placed on classifying close contacts for tracing #Covid_19 transmission.
As @jmcrookston puts it, no one knows for sure why 15 minutes and believe me, if he is not sure, no one is. No one has looked harder. A
1/7
As @jmcrookston puts it, no one knows for sure why 15 minutes and believe me, if he is not sure, no one is. No one has looked harder. A
1/7
Gradually over the year though, evidence started emerging that the virus does not wear a watch, i.e., 15 minutes is not a magical barrier.
Busting the 15-minute myth further: 2/7
Busting the 15-minute myth further: 2/7
https://www.cdc.gov/mmwr/volumes/69/wr/mm6943e1.htm Outbreak in a prison. Correctional officer infected with ~17 minutes of cumulative exposure, not continuos, and he was wearing masks during all interactions 3/7
Revised guidance from CDC. "Individual who has had close contact (within 6 feet for a total of 15 minutes or more)" Now 15 mins or more, cumulative, over 24 hours.
https://www.cdc.gov/coronavirus/2019-ncov/php/public-health-recommendations.html 4/7
https://www.cdc.gov/coronavirus/2019-ncov/php/public-health-recommendations.html 4/7
Two infections, from one person, seated over 4 meters away. One infection in ~5 minutes spent in same room 5/7 https://jkms.org/DOIx.php?id=10.3346/jkms.2020.35.e415
"National Football League observed SARS-CoV-2 transmission after <15 minutes of cumulative interaction, leading to a revised definition of a high-risk contact that evaluated mask use and ventilation in addition to duration and proximity" 6/7 https://www.cdc.gov/mmwr/volumes/70/wr/mm7004e2.htm?s_cid=mm7004e2_w
So 15 minutes is not magical, neither is 2/1.5/1 m
There is no absolute guarantee of safety.
To reduce your chances of getting infected, reduce time in contact, #MaskUp, keep as much distance as possible, avoid crowds and indoors, #ventilate #FreshAir #UseAirbornePrecautions 7/7
There is no absolute guarantee of safety.
To reduce your chances of getting infected, reduce time in contact, #MaskUp, keep as much distance as possible, avoid crowds and indoors, #ventilate #FreshAir #UseAirbornePrecautions 7/7
And I could not think of a better way to put the complexity of defining close contact than quoting this thread from Prof. Corsi ( @CorsIAQ) https://twitter.com/CorsIAQ/status/1326744878609436672
